1. Field of the Invention
The present invention relates to a valve suitable for a fluid control device that charges compressed air into an air reservoir and exhausts the air from the air reservoir, and relates to the fluid control device.
2. Description of the Related Art
A conventional electronic sphygmomanometer is disclosed in Japanese Examined Utility Model Application Publication No. 61-32645. This electronic sphygmomanometer is connected to a cuff through an armband rubber tube. This electronic sphygmomanometer stores in a body case: a pressure pump that sends air out to the cuff; a pressure sensor that converts a cuff pressure into an electronic signal; an electromagnetic valve that is opened according to the electric signal, and rapidly reduces the cuff pressure; a constant speed reducing pressure valve that reduces the cuff pressure at a constant speed; and a driver circuit that generates an electric signal and transmits the electric signal to the electromagnetic valve. The pressure sensor, the pressure pump, the electromagnetic valve, and the constant speed reducing pressure valve are connected to one another by one rubber tube, and this one rubber tube is connected to an arm band rubber tube that communicates with the cuff.
In this structure, the electronic sphygmomanometer, when starting blood pressure measurement, sends out air to the cuff by the pumping operation of the pressure pump, and increases the pressure in the cuff. Then, after the blood pressure measurement is completed, the electronic sphygmomanometer energizes the electromagnetic valve, opens the electromagnetic valve, and makes air in the cuff exhaust rapidly. Accordingly, the cuff will be in a state in which the next blood pressure can be measured.
The electronic sphygmomanometer of Japanese Examined Utility Model Application Publication No. 61-32645 requires an electromagnetic valve that is difficult to be miniaturized and a driver circuit that drives the electromagnetic valve. Therefore, the manufacturing costs may become higher, and the main body of the electronic sphygmomanometer may become larger, and the power consumption may increase.
Accordingly, for example, in order to simplify the structure, a typical piezoelectric pump might be connected to a cuff directly. For example, a piezoelectric pump having a pump housing with a pump chamber, a discharge hole, and a suction hole formed inside is prepared; and the discharge hole is connected to the armband rubber tube of the cuff. Then, the piezoelectric pump, when starting blood pressure measurement, performs a pumping operation, sends out air from the discharge hole to the cuff, and increases the pressure in the cuff. Subsequently, after the blood pressure measurement is completed, the piezoelectric pump stops the pumping operation and exhausts the air in the cuff from the suction hole.
However, the volume of the air that can be stored in the cuff is extremely large as compared with the volume of the pump chamber of the piezoelectric pump. Then, the exhaust speed of the piezoelectric pump is extremely slow as compared with the amount of the air that can be stored in the cuff. Therefore, in a case in which the piezoelectric pump is directly connected to the cuff, the air in the cuff cannot be exhausted rapidly.